A water removal system of the type referred to above and adapted for use with vacuum toilets having a manually operated cut-off valve, is described, for example, in German Pat. No. 1,302,597. In other known facilities wherein waste water is collected, an automatic check valve can be used, i.e., a valve whose operation is controlled as a function of the system water level or as a function of time.
In other conventional systems, waste water from several different facilities is first allowed to flow through gravity feed lines into a collector receptacle which is connected to a vacuum waste water removal conduit through a cut-off valve, the cut-off valve being controlled as a function of the level of the water in the receptacle and being emptied when a specific level is reached. An example of such a system is disclosed in German Patent No. OS 2,455,551.
The two different types of vacuum water removal systems mentioned above are always installed individually. In some cases the systems are employed in addition to conventional water removal systems including gravity feed lines, but in parallel therewith to, and always independently of each other. Therefore, any efforts made hereintofore to solve technical difficulties and problems have been concentrated on special measures taken with respect to the individual systems themselves.
There is a special problem in waste water facilities such as toilets, water collectors and the like which are directly connected via a cut-off valve to a vacuum waste water removal conduit. Specifically, in such systems the cut-off valve is designed to always remain in a tightly closed state, and to open only briefly during the emptying process. If, because of a detect in the water supply (e.g., a leaky faucet or water intake in a vacuum toilet), or in the control of the cut-off valve (e.g., because of a failure of the vacuum in the system, or due to clogging or seizing) and a resultant unintentional and unnoticed water flow when the cut-off valve is closed, a serious overflow problem can result. This problem of possible overflow has been known as long as vacuum toilets have been in existence.
An attempt has been made to eliminate the problem through the use of automatic controls for the cut-off valve which automatically open the valve when the associated facility reaches a specific filling level and which close the valve again after emptying. Automatic controls providing such safety precautions are relatively complicated and expensive. In addition, such controls are subject to failure.